Exhast Help?

Hey You guys, I bought this OBX high flow cat. It really isn't a cat though, it has 2.5 inch openings on each end. But when you look inside it's got a one inch pipe down the center with sheet metal that swirls around the outside of it, all inside the part were the cat material usually is. The thing is I dont think there is as much punch as there use to be, like there is a lack of torque in the low end :disappoin . So should I put the original cat back in, Keep it this way or knock out all the center pipe and swirl crap and weld a staight pipe in?? I am planning to put stage 1 cams in with springs and retainers, would this make the difference(I mean make better use) with the exhast?? Little help here.